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  Background: Human serum albumin (HSA) is a soluble blood protein which can bind to small molecules (such as drugs and toxins) and transfer them within the blood circulation.

  Materials and Methods: UV-Vis spectroscopy and FT-IR methods were used to characterize the binding properties of HSA with diazinon(the toxin of organophosphate) and to investigate the changes of protein secondary structure, respectively, in molecular level under physiological condition in two times of first and thirty five days .

  Results: The binding constant (K_Diazinon-HSA = 3.367 ) was have been calculated based UV-Vis spectroscopy data. In FT-IR method, the proportion of decrease in percentage of &alpha-Helix on the first day was 53.97% to 51.88%, other secondary structures increased, such as Turns from 8.49% to10.21%, ß-Sheet from 13.94% to 14.81%, &beta-anti from 8.2% to %8.25 and r-coils from 15.4% to % 17.24. These changes for &alpha-Helixes, Turns, ß-Sheet, &beta- anti and random r-coils after thirty five days were 56.7% to 47.11%, 25.3% to 29.75%, 6.93% to 10.94%, 2% to 2.83% and 9.08% to 10.86%, respectively.

Conclusion: Since the content of protein secondary structure relates closely with its biological activity, therefore, a decrease in &alpha-helix and increase in &beta-sheet structure in the presence of diazinon at high concentration means the decrease of HSA biological activity. Our results suggest that diazinon has a relatively good binding with HSA and it could cause considerable changes in various secondary structures and likely is indicative of a unfolding of protein especially for the samples in thirty five days .

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Background and Aim: Tamoxifen is a group of drugs of selective estrogen receptor modulators, and is one of the drugs effective in the prevention and treatment of some cancers (such as breast cancer). In this study, the interaction of tamoxifen with DNA is investigated experimentally. Also, the electronic structure (at atomic scale) of the molecular system of tamoxifen was theoretically investigated, using atom in molecule (AIM) theory.
Methods & Materials: First, in the experimental section of this study, the interaction of Tamoxifen with DNA were investigated by UV-ViS technique and hydrodynamic method (Viscometry). In addition, the analysis of the experimental results shows the obvious effect of concentration on the mechanism of how the tamoxifen molecule binds to DNA. Then, in the theoretical part of this research, using computational biophysical chemistry methods, some properties of tamoxifen molecular system, such as electronic Density of States (DOS), boundary orbital’s energy (HOMO/LUMO), Electrostatic Potential Energy (EPS) and electronic contour maps of the electron density and its Laplacian, will be calculated.
Ethical Considerations: This article is a meta-analysis with animal sample.
Results: Result of the UV-ViS spectroscopy technique and viscometry indicated hyperchromism and hypochromism effect. In addition, the result were depend on the concentration of the drug and affected the kind of binding of Tamoxifen to DNA. the analysis of computational studies on the drug tamoxifen suggests that the mechanism of the local charge/energy distribution in the molecular system of tamoxifen plays an important role in how this drug binds to DNA.
Conclusion: Based on the experimental results of UV-ViS technique and viscometry, as well as the electronic/vibrational properties of the tamoxifen molecular system, it was defined that the Tamoxifen interacts significantly with all the binding sites of DNA.